Some terms appear in these pages that may not be familiar to most people. I have tried to list most of those here.
Accommodation: focusing of the eyes; focusing must relax to see at a distance and must engage close up – think of an open hand versus a clenched fist; the muscles of the hand are relaxed when the hand is open, they are tightened up when clenching a fist. There are muscles in the eye that flex and relax with changing focus, but the important part of the process occurs in the brain. This ability can be improved with vision therapy.
Amblyopia: commonly known as lazy eye;defined as a difference of two or more lines on the eye chart with best corrected vision. If one eye is unable to see as well as the other and there is no physical reason such as disease or injury then amblyopia is present. Amblyopia can usually be improved with vision therapy.
Analytical: a series of 21 probes of the visual system used by behavioral optometrists to determine the appropriate lenses needed to satisfy the functional needs of the individual. It is also used to determine the reasons for decreased visual performance as well as the possible treatment modes and likelihood of success.
Brock String: created by Fred Brock; one end of a string is held against the nose with the far end attached to a wall, etc. The person looks at a particular location on the string and is given immediate feedback as to quality of eye teaming, focusing and eye movements.
Diplopia: double vision. When the eyes are not pointing at the same thing at the same time there will either be double vision or the brain will ignore or suppress the input from one eye. Most doctors prescribe prisms to mask the double vision. Behavioral optometrists prefer to treat diplopia using vision therapy. Diplopia is often treated successfully with vision therapy.
Esotropia (convergent strabismus): condition where the eyes are not teaming accurately, specifically, the eyes are aimed at a point in space that is closer than the object of regard. This causes the image to appear doubled horizontally unless the brain has learned to ignore one of the images (suppression) in order to avoid confusion.
Exotropia (divergent strabismus): condition where the eyes are not teaming accurately, specifically, the eyes are aimed at a point in space that is farther than the object of regard. This causes the image to appear doubled horizontally unless the brain has learned to ignore one of the images (suppression) in order to avoid confusion.
Optical infinity: typically considered to be at twenty feet from the eyes and considered to be the point in space where focusing is completely relaxed.
Retinoscopy: a rapidly disappearing probe of the focusing abilities; that is the ability to focus in the far distance, the ability to focus at the working distance, the ability to maintain flexible or stable focus as needed. This probe is being replaced by autorefraction. Autorefraction is a mechanical means of measuring distance focus. This technique provides only a small percentage of the information that can be obtained doing manual retinoscopy.
SILO: during certain activities in Vision Training (and actually in natural situations) the use of lenses and prisms should create the sensation/perception that objects coming closer appear to get smaller while those moving away appear to get larger.
Strabismus: condition where the eyes are not teaming accurately; esotropia is one type, exotropia (divergent strabismus) -eyes pointing further in space than object of regard, vertical strabismus (object appears doubled vertically) are others. Any of these may be constant, intermittent or may appear to involve only one eye or both.
Vergence: the ability of the eyes to point together at various distances in space.
Visual acuity: what is measured by reading the eye chart. 20/20 is average visual acuity. Not everyone can see this well and some people can see better than this. Most lenses are prescribed merely to cause a person to see 20/20.
Visual training (visual therapy, vision training, vision therapy): a program of visual and visually related activities used to correct functional visual problems, enhance visual performance related to learning, earning and sports.